Chemotherapy gets personal for cancer patients

U-M researchers evaluate more effective way to determine the best chemotherapy dose for breast cancer patients

originally posted October 1, 2001

ANN ARBOR, Mich. - Chemotherapy has long
been known to be an effective way to control the spread of
cancer. But its benefits don't come without the price of possible
devastating side effects including hair loss and fatigue.
Sometimes without warning, even more serious side effects
can happen which result in illness and hospitalization. Now,
a new study may have found a way to eliminate the unpredictability
of chemotherapy without jeopardizing the treatment.

Physicians at the University of Michigan Health
System's Comprehensive Cancer Center are conducting a study
on chemotherapy doses for breast cancer patients. This population,
according to Anne Schott, M.D., medical oncologist at the
Cancer Center and assistant professor of hematology/oncology,
often has chemotherapy prescribed to them as a form of treatment.

"For a woman who has just been diagnosed with
breast cancer, her treatment options include chemotherapy,
as well as surgery, hormonal therapy, and radiation treatments,"
she says. "But to control the cancer spreading, usually most
cases require chemotherapy."

Chemotherapy is the treatment of cancer with
drugs that can destroy cancer cells. The body, usually the
liver or the kidneys, breaks down the medication. The amount
of chemotherapy given is most often based on a patient's height
and weight. But this method does not always lead to the best
dose for patients.

"Schott explains, "The problem with that approach
is it doesn't take into account an individual's metabolism
of chemotherapy, which could vary greatly depending on what
medicines they are on, what their heart function is, what
their liver function is, and what their kidney function is."

Researchers at the Cancer Center are trying
to fix the problem by tailoring doses with results from the
Erythromycin Breath Test, a test - originally developed at
the U-M - that can determine how a patient's body breaks down
the antibiotic erythromycin. Erythromycin is metabolized in
the same way as many chemotherapy drugs, by the enzyme CYP3A4.

"We're using the Erythromycin Breath Test to
tell us how fast an individual will metabolize other drugs
that use the same enzyme," she says. "In the study we're conducting,
we're looking at the breast cancer drug Taxotere, which uses
that same enzyme, to tell us how to dose the chemotherapy
drug.

The Erythromycin Breath Test works like this.
The patient gets an injection of a very small and safe amount
of radioactive erythromycin. After they get the injection,
they wait 20 minutes for the drug to be metabolized and then
they blow air out into a bag. From there, doctors can measure
traces of carbon dioxide in their breath. Carbon dioxide is
one of the chemicals produced when erythromycin is broken
down by the body.

"By using the Breath test, we can actually pick
a dose of Taxotere that's specificfor the individual, not
just based on their height and weight," Schott notes. "By
picking a dose that's specific for the individual, we will
not have the risk of either overdosing or underdosing the
individual."

This is very important since chemotherapy drugs
can harm healthy cells, causing side effects. With the use
of tailored doses of chemotherapy drugs, it is hoped that
patients will be less likely to experience those side effects.

Some study participants have already reported
a positive effect. Gretchen Davenport was diagnosed with breast
cancer in 1998. When it came back a year later, she enrolled
in the Cancer Center study."In my first run of chemotherapy
almost 4 years ago, I was very tired and had to have Neupogen,"
Davenport says. "But the cancer came back and I had to have
chemotherapy again, so I came here to the Cancer Center. This
time I had very few side effects. I wasn't tired and never
lost my appetite."

Preliminary results show that tailored dosing
allows doctors to achieve more consistent drug levels in the
body, compared to just giving everyone the standard dose.
Consistent drug levels are critical in fighting cancer cells.
"We think it's very important to make sure we're still seeing
the same effectiveness of the drug in the tailored dosing
as we would if we gave the standard dose," Schott notes.

Schott says although the drug Taxotere is being
testing in the current study, other chemotherapy drugs are
not being ruled out. "We've chosen Taxotere as really a proof
of principle that this sort of tailoring will work," Schott
says. "Once this study is completed, we will expand to include
drugs which have the same kind of metabolism."

Gretchen Davenport hopes all women suffering
with breast cancer can some day take advantage of tailored
chemotherapy dosing. "I think it's wonderful what they can
do," she says. "It makes you feel a lot better about getting
chemotherapy, that you're getting a dose that's specifically
for you."

The study at the Cancr Center has already shown
promise on a small group of breast cancer patients. Currently,
researchers are enrolling women with breast cancer who would
benefit from Taxotere. For more information on the tailored
dosing study contact the UMHS Cancer AnswerLine™ at 1-800-865-1125.

Facts about chemotherapy:

Chemotherapy is the treatment of cancer with drugs that
can destroy cancer cells. These drugs are often called "anticancer"
drugs.

Chemotherapy can be used to cure, control, or relieve
symptoms that cancer may cause.

At times, chemotherapy is used with other treatments including
surgery, radiation therapy, and/or biological therapy.

The duration of chemotherapy treatment depends on the
kind of cancer, the goals of the treatment, the drugs that
are used, and how a patient's body responds to drugs.

Chemotherapy can also harm healthy cells, causing side
effects. Common side effects are: fatigue, nausea and vomiting,
pain, lowering of blood counts, and hair loss.

Facts about breast cancer:

About one out of every eight American women will develop
breast cancer sometime during her life.

Every year, about 180,000 women are diagnosed with breast
cancer. The risk of developing breast cancer increases
beyond age 35, and is higher if a close relative has had
breast cancer.